PHP Removing and Inserting Elements in an Array

$arr = explode(',','3,5,9,11');
$add_value = 26;
$del_value = 9;

Inserting

if(!in_array($add_value, $arr)) {
	array_push($arr,$add_value); 
}
Array (
	[0] => 3
	[1] => 5
	[2] => 9
	[3] => 11
	[4] => 26
)

Removing

if(in_array($del_value,$arr)) {
	unset ($arr[array_search($del_value,$arr)]);
}
Array (
	[0] => 3
	[1] => 5
	[3] => 11
	[4] => 26
)